Methods and systems for scatter estimation in positron emission tomography

Abstract

Methods and systems for multiple scatter estimation in Positron Emission Tomography (PET) are provided. One method includes determining attenuation sinograms and determining a varying convolution kernel as a function of the attenuation sinograms, wherein the kernel varies in amplitude and width over a radial length of a PET imaging system. The method also includes using the varying convolution kernel to estimate multiple PET scatter.

What is claimed is: 
     
       1. A non-transitory computer readable storage medium for estimating multiple scatter in Positron Emission Tomography (PET) imaging using a processor, the non-transitory computer readable storage medium including instructions to command the processor to:
 determine attenuation sinograms; 
 determine a position-varying convolution kernel as a function of the attenuation sinograms, the kernel varying in amplitude and width over a radial length of a PET imaging system; and 
 use the position-varying convolution kernel to estimate multiple PET scatter. 
 
     
     
       2. The non-transitory computer readable storage medium of  claim 1 , wherein the attenuation sinograms are determined from one of a Computed Tomography (CT) scan or a Magnetic Resonance (MR) scan and the instructions further command the processor to determine the position-varying convolution kernel with a Gaussian distribution of a CT attenuation map or an MR attenuation map using the attenuation sinograms. 
     
     
       3. The non-transitory computer readable storage medium of  claim 1 , wherein the instructions further command the processor to determine the position-varying convolution kernel using a single scatter distribution profile and a multiple scatter distribution profile, the single scatter distribution profile and the multiple scatter distribution profile determined from one or more simulations. 
     
     
       4. The non-transitory computer readable storage medium of  claim 3 , wherein the simulation is one of PET scanner specific or PET scanner configuration specific. 
     
     
       5. The non-transitory computer readable storage medium of  claim 4 , wherein a plurality of parameters used to determine the position-varying convolution kernel are determined from the one or more simulations, wherein one parameter defines a width of a Gaussian kernel to filter a path length sinogram and a plurality of additional parameters define linear coefficients of a single to multiple convolution kernel amplitude and width. 
     
     
       6. The non-transitory computer readable storage medium of  claim 1 , wherein the attenuation sinograms comprise filtered attenuation sinograms. 
     
     
       7. The non-transitory computer readable storage medium of  claim 1 , wherein the instructions further command the processor to use Time-of-Flight (TOF) information to determine the position-varying convolution kernel. 
     
     
       8. The non-transitory computer readable storage medium of  claim 1 , wherein the instructions command the processor to filter the amplitude and width with a determined path length. 
     
     
       9. A method for estimating multiple scatter in Positron Emission Tomography (PET) imaging, the method comprising:
 determining attenuation sinograms; 
 determining a position-varying convolution kernel as a function of the attenuation sinograms, the kernel varying in amplitude and width over a radial length of a PET imaging system; and 
 using the position-varying convolution kernel to estimate multiple PET scatter. 
 
     
     
       10. The method of  claim 9 , wherein the attenuation sinograms are determined from one of a Computed Tomography (CT) scan or a Magnetic Resonance (MR) scan and further comprising determining the position-varying convolution kernel with a Gaussian distribution of a CT attenuation map or an MR attenuation map using the attenuation sinograms. 
     
     
       11. The method of  claim 9 , further comprising determining the position-varying convolution kernel using a single scatter distribution profile and a multiple scatter distribution profile, the single scatter distribution profile and the multiple scatter distribution profile determined from one or more simulations, wherein the simulation is one of PET scanner specific or PET scanner configuration specific. 
     
     
       12. The method of  claim 11 , wherein a plurality of parameters used to determine the position-varying convolution kernel are determined from the one or more simulations, wherein one parameter defines a width of a Gaussian kernel to filter a path length sinogram and a plurality of additional parameters define linear coefficients of a single to multiple convolution kernel amplitude and width. 
     
     
       13. The method of  claim 9 , further comprising using Time-of-Flight (TOF) information to determine the position-varying convolution kernel. 
     
     
       14. The method of  claim 9 , further comprising filtering the amplitude and width with a determined path length. 
     
     
       15. A Positron Emission Tomography (PET) imaging system comprising:
 a gantry; 
 a detector ring mounted to the gantry, the detector ring having a plurality of detector elements; and 
 a scatter estimation module configured to (i) determine attenuation sinograms, (ii) determine a position-varying convolution kernel as a function of the attenuation sinograms, the kernel varying in amplitude and width over a radial length of the gantry, and (iii) use the position-varying convolution kernel to estimate multiple PET scatter. 
 
     
     
       16. The PET imaging system of  claim 15 , wherein the attenuation sinograms are determined from one of a Computed Tomography (CT) scan or a Magnetic Resonance (MR) scan and further comprising a CT imaging portion or an MR portion and wherein the scatter estimation module is further configured to determine the position-varying convolution kernel with a Gaussian distribution of a CT attenuation map or MR attenuation map using the attenuation sinograms determined from CT data or MR data acquired from the CT imaging portion or the MR imaging portion. 
     
     
       17. The PET imaging system of  claim 15 , wherein the scatter estimation module is further configured to determine the position-varying convolution kernel using a single scatter distribution profile and a multiple scatter distribution profile, the single scatter distribution profile and the multiple scatter distribution profile determined from one or more simulations, wherein the simulation is one of PET scanner specific or PET scanner configuration specific. 
     
     
       18. The PET imaging system of  claim 17 , wherein a plurality of parameters used to determine the position-varying convolution kernel are determined from the one or more simulations, wherein one parameter defines a width of a Gaussian kernel to filter a path length sinogram and a plurality of additional parameters define linear coefficients of a single to multiple convolution kernel amplitude and width. 
     
     
       19. The PET imaging system of  claim 15 , wherein the scatter estimation module is further configured to use Time-of-Flight (TOF) information to determine the position-varying convolution kernel. 
     
     
       20. The PET imaging system of  claim 15 , wherein the scatter estimation module is further configured to filter the amplitude and width with a determined path length.